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Level 1B
Instrument Performance History

Optical cross-talk (Band 31 into Bands 32 – 36)

Description | L1B Impact | L2 Impact | Cause | Mitigation | Schedule | History

DESCRIPTION:

Terra MODIS Band 31 (11 µm) leaks energy into Bands 32-36 (12-14 µm).

IMPACT TO L1B DATA SET:

With a light leak from Band 31 (sensitive to signals from the surface), "ghosts" from surface features are seen in the images for Bands 32-36. The size of this cross-talk generally depends on the separation on the focal plane from the location of Band 31. The correction applied to Bands 32 - 36 after August 10, 2000 is approximately 1%, 1%, 3.5%, 8.3% and 6.5%, respectively, of the Band 31 signal.

ESTIMATED IMPACT TO L2 SCIENCE PRODUCTS:

With a light leak from Band 31 (sensitive to signals from the surface), "ghosts" from surface features are seen in the images for Bands 32-36. The size of this cross-talk generally depends on the separation on the focal plane from the location of Band 31. The correction applied to Bands 32 - 36 after August 10, 2000 is approximately 1%, 1%, 3.5%, 8.3% and 6.5% of the Band 31 signal, respectively.

CAUSE OF EFFECT:

This optical cross-talk is caused by scattering off the bottom edge of the Band 31 spectral filter. The scattered energy is reflected between the filters and the detectors for Bands 32-36.

MITIGATION APPROACH/ADDED TESTING TO CHARACTERIZE EFFECT:

Corrections have been applied based on pre-launch testing and on-orbit studies (moon observation and SRCA data), including studies of these ghosts. The correction used for Bands 32 - 36 August 10, 2000 is approximately 1%, 1%, 3.5%, 8.3% and 6.5%, respectively, of the Band 31 signal.

ESTIMATED SCHEDULE TO COMPLETE:

The correction is used in the present product after August 10, 2000.

HISTORY OF CHARACTERISTIC:

Description | L1B Impact | L2 Impact | Cause | Mitigation | Schedule | History

Please contact Jack Xiong with any technical questions concerning these pages.

Responsible Civil Servant: 
Dr. Jack Xiong <Xiaoxiong.Xiong.1@gsfc.nasa.gov>

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Last Update:  July 3, 2008